Method for cleaning combustion devices

ABSTRACT

The invention is related to a so-called on-line method and a device for the cleaning of contamination with dirt, resp., caking or slag deposits in vessels and combustion installations by means of blasting technology. For this purpose, an explosive gas mixture is made to detonate in the proximity of the contamination with dirt, resp., caking or slag deposits.

[0001] The invention relates to a method and to a device for cleaningvessels contaminated with dirt, resp. with slag or ashes. In particularit is related to a method and to a device for the so-called on-lineblast cleaning of combustion installations in accordance with thepreamble of the independent claims.

[0002] Heating surfaces, e.g. of waste incineration plants or of coalfired boilers in general are subject to a strong contamination withdirt. These types of dirt normally have inorganic compositions and aretypically produced by deposits of ash particles on the walls. Areas inthe zone of high flue gas temperatures are in most instances very hard,because they remain stuck to the walls either in molten form or meltedon form or else are stuck together on the wall by substances melting orcondensing at lower temperatures, when these solidify on the colderboiler wall. Coatings of this kind can only be removed with difficultyand unsatisfactorily by known cleaning methods. This leads to theconsequence, that the boiler has to be switched off periodically, cooleddown and cleaned either manually or by means of sand-blasting. Becauseboilers of this kind in most instances have very large dimensions, it isfrequently necessary to install a scaffolding in the furnace for thispurpose. This additionally necessitates an interruption of the operationlasting several days or weeks and apart from this, because of thesubstantial dust—and dirt emissions it is exceedingly unpleasant andunhealthy for the cleaning personnel. A usually unavoidable accompanyingphenomenon of the interrupted operation of an installation are damagesto the vessel materials themselves as a consequence of the greattemperature changes. Apart from the cleaning—and repair costs, thestand-still costs of the installation due to the production—resp. incomelosses represent an important overall cost factor.

[0003] Conventional cleaning methods, for example, are boiler beatingand the utilisation of steam-jet cleaners, water-jet blowers/sootblowers and shot peening.

[0004] Known is a cleaning method, in the case of which the cooleddown—and also the hot boiler still in operation is cleaned by means ofthe introduction and igniting of explosive devices. In the case of themethod described in the document EP 1 067 349, a cooled explosive deviceby means of a cooled lance is brought into the proximity of the heatingsurface contaminated with dirt, where the explosive device is thenignited. The cakings on the heating surfaces are blasted off by force ofthe detonation, as well as by the vibrations of the wall produced by theshock waves. With this method, the cleaning time in comparison with theconventional cleaning methods is able to be reduced significantly. Withthe necessary safety precautions, the cleaning can take place on-line,i.e., during the operation of the combustion furnace, resp. while thevessel is still in a hot condition. With this method, it is possible toclean a boiler within hours, while with a conventional cleaning methoddays would be required for this.

[0005] Disadvantageous in the case of the method described in EP 1 067349 is the necessity of explosives. Apart from the high costs of theexplosive material, in order to avoid accidents, for example, during thestorage of the explosive material, elaborate security precautions haveto be undertaken. The introduction of explosive material into a hotvessel in addition calls for an absolutely reliable and efficientcooling system, in order to prevent a premature detonation of theexplosive material.

[0006] It is the objective of the invention to create a method and adevice for the cleaning of combustion installations or vesselscontaminated with dirt, resp. with slag, with which the installationdoes not have to be shut-down during the cleaning operation, with whichthe installation is in a clean condition again in a short time andespecially with which any endangering of personnel and of installationcomponents during the cleaning process is minimised.

[0007] The objective is achieved by the invention, as it is defined inthe claims.

[0008] The cleaning method disclosed here is based on bringing gaseous,liquid and/or powdery materials resp. components, which are eitherindividually explosive or in preference only explosive as a mixture,into the proximity of an object to be cleaned, in order to subsequentlyget the at least partially gaseous explosive mixture to detonate.

[0009] For the protection of people, the materials should be able to bestored and handled separately, in order to if at all possible be able toexclude the hazard of a premature explosion. This is possible with thecleaning method in accordance with the invention, because the explosivematerial or the explosive mixture is capable of being produced at thepoint or in the vicinity of the point of a vessel, in which it is to beutilised. This enhances the safety for persons and objects. With thecleaning device according to the invention, during an introduction—andpositioning process of the device no explosive materials or componentsare present yet and therefore also not exposed to the prevailing heat.

[0010] The cleaning process in accordance with the invention isparticularly suitable for combustion installations with sticky, fly ashwith a tendency to caking, which is produced especially by thecombustion of coal, refuse, sewage sludge or hazardous waste materials.This is applicable in particular in the field of steam generators ofcombustion installations. The cleaning process, however, may also beapplied for the removal of dirt in other installations with harddeposits of dirt, such as, e.g., in flue gas cleaning installations,paper mills, silos, in the cement industry, etc. The blast cleaning isable to be carried out during the operation of a plant, i.e., on-line orwith the vessels still hot and exceedingly purposefully and preciselydosed. As a result, the plant down-time costs are reduced and nocomponents of the installation or sections of the vessel areunnecessarily subjected to any load. The hazards for the personnel ofthe plant are also minimised. This in particular as a result of theexceedingly short dwell time of the at least partially gaseous explosivecomponents or of the mixture in the hot ambient.

[0011] In a preferred embodiment of the cleaning method according to theinvention, a fuel, in liquid or gaseous form, e.g. acetylene, ethylene,methane, ethane, propane, petrol (gasoline), oil, etc. and an oxidisingagent, e.g., oxygen, are brought into the proximity of a surface to becleaned. There the components are mixed together and subsequentlyignited. The force of the detonation and the surface made to vibrate bythe shock waves, e.g. a wall of a vessel or of a pipe, cause thebreaking off of the cakings on the walls and with this the cleaning ofthe surface. The components can also be mixed together in the deviceaccording to the invention.

[0012] The force of the explosion necessary for cleaning and with thisthe quantity of the materials used is dependent on the type ofcontamination with dirt and on the size of the dirty vessel. The dosingand the force of the explosion are able to be and are selected in such amanner, that no damage to the installation occurs. For example, themixed gas quantity of acetylene and oxygen necessary for an effectivecleaning lies between 5 and 30 litres per explosion. The optimum mixingratio of the gases can be calculated from the stoichiometry of the gasesand in the case of acetylene and oxygen it amounts to 1:3. In the caseof an explosive gas mixture of oxygen and acetylene, the ratio is at3.5:1 with a total gas volume of, for example, approx. 100 litres. Thepossibility of the optimum dosing of the components utilised on the onehand reduces the cleaning costs and on the other hand also reduces thehazard—and damage risk for the installation and for human beings.

[0013] An in preference pipe-like device, e.g. a lance, is introducedinto an installation resp. into a vessel and brought into the proximityof the place to be cleaned. By means of this device, after thepositioning of the device the component or the components are able to beintroduced into the installation resp. into the vessel. In the case ofan on-line cleaning operation, the vessel to be cleaned and, e.g. theflue gas may be up to 1000° C. hot. This signifies, that for theprevention of a premature explosion the materials utilised for cleaning,e.g. gases and fuels, should be brought to the desired place morerapidly than they are capable of being heated up by, e.g. heatradiation. The pipe is in preference thermally insulated and/or cooled.This can be achieved by a pipe made out of thermally insulatingmaterials resp. by a cooling system attached to the pipe or conductedthrough the pipe. The cooling for a pipe and/or for the materialsutilised for the cleaning is preferably designed in such a manner, thatit is capable of functioning without a continuous supply of coolant fromoutside into the cleaning device or to the components or to theexplosive mixture of gas, respectively. A pipe or a lance thereforewould only have to be equipped with the connections for the, forexample, gaseous components and correspondingly could be designed to bemore simple. A cleaning device of this type is also not dependent on,e.g. water connections in the vicinity of the object to be cleaned. Iffor the cooling a coolant, such as, for example, water is utilised asinsulation material for the lance, then for this purpose connectionshave to be attached to the lance. Any hoses required could, if sodesired, be removed prior to the actual utilisation of the lance for thecleaning operation. If a cooling of the lance in a positioned conditionby means of a flow of coolant is necessary, then this in preference iseffected by conducting a coolant through the lance, so that it flowsdirectly into the hot vessel. A cleaning device, however, may also bedesigned in such a manner, that a coolant flows back again inside thedevice. In order to completely preclude the possibility of a prematureexplosion, the explosive, at least partially gaseous mixture ispreferably only produced at the point, where the explosion is to takeplace. This is implemented, for example, by mixing a combustible gas andan oxidising agent in the vessel itself, which is to be cleaned. It is,however, also possible to already bring together the individualcomponents in a part of a supply line, e.g., inside the lance. As aresult of this, the thorough mixing of individual components is alreadystarted shortly before the place to be cleaned. With the necessarysafety precautions, it is also possible to directly introduce anexplosive gas or gas mixture into an installation resp. into a vessel.Also in the case of this variant, the hazard of a premature explosion ofexplosive materials or mixtures is minimal, because the introduction ofa device and a possibly required positioning of it is able to be carriedout beforehand and therefore completely without the presence of anyexplosive materials. If instead of gaseous materials one or morematerials in liquid or powder form, e.g. fuels, are utilised, then theseare conducted to the place to be cleaned through e.g. the pipe-likedevice by means of a suitable pumping device, where the material ormaterials in liquid or powder form is, resp. are, in preferencenebulised or atomised. This can be implemented, for example, by apressure—or gas atomisation, e.g. by using a gas utilised in thecleaning operation.

[0014] The dosing of gases, resp. of gas mixtures, possibly also ofliquid materials, takes place preferably by means of pressure vessels.Beforehand, precisely dosed quantities of gas resp. liquid can beintroduced into these pressure vessels, e.g. by means of controlledfilling from commercially available gas cylinders. The utilisation ofseparate pressure vessels provides the benefit, that the quantities andwith this the fill pressures in these vessels are capable of beingadapted to the desired force of the explosion in a very simple manner.In addition, by the introduction of the gases or liquids under pressure,the dwell time of the components in the hot ambient is able to be keptexceedingly short.

[0015] In order to prevent a dilution of gases, gas mixtures, materialsin powder or liquid form, e.g. by the ambient air or flue gas, thematerials are preferably held at or in the proximity of the place to becleaned, for example, by means of a suitable thin-walled container. Thisis particularly advantageous in such cases, where an explosive mixtureis to be produced only in the proximity of the surface to be cleaned,for example, by a separate conducting of individual gases or fuels in apipe-like device or a lance, resp. A vessel of this kind, i.a., servesfor preventing a dilution of the gases, in particular prior to theircomplete mixing and if so required also serves for their cooling.Examples of suitable thin-walled containers are expanding, thin-walled,balloon-like containers, or flexible, elastic, thin-walled containers,such as, for example, sack-like envelopes or sacks. A thin-walledcontainer is preferably attached to one end of a pipe, e.g., at thefront end of the lance and is inflated by the gases themselves. In orderto prevent a premature explosion of the thin-walled container, it shouldbe inflated more rapidly than it heats up as a result of convection orradiation and/or it should be cooled. In preference, the thin-walledcontainers have a greater volume than the total volume of the componentsintroduced into them. On the one hand, this prevents a prematuredestruction of the thin-walled container by bursting, e.g. of elastic,balloon-like container. On the other hand, for example, in the case ofcontainers made out of non-expanding materials, such as, for example,sack-like plastic or paper envelopes, there is no overpressure in thecontainer relative to the ambient. This prevents or minimises anyoutflow of gas in the case of permeable materials or in the case of apossible perforation of the thin-walled container, which could becaused, for example, by sparks or by sharp objects.

[0016] A front end cooling of the lance resp. the cooling of athin-walled container is implemented in preference by means of passivecooling methods. In the case of a passive cooling of an explosive gasmixture, in the introduced condition of the cleaning device noadditional cooling means are brought in from the outside to or into theexplosive mixture. Apart from general constructional simplifications ofthe cleaning device this also has the advantage that supply lines forthe materials required for the explosion can relatively easily be keptseparate from a possible lance cooling system. In the case of acombination with a passive lance cooling system, the complete cleaningprocess is able to be kept essentially independent of a locallyavailable infrastructure.

[0017] A thin-walled container, and therefore also the materialscontained in it, is capable of being protected against undesirably highheating-up by means of a thermal insulating protective envelope or bymeans of a protective envelope already containing a coolant. An examplefor the latter kind of protective envelope can be designed in a verysimple manner and, for example, would comprise a material as absorbentas possible, e.g. crepe or a sponge-like material, which prior to beingintroduced into the hot installation is soaked with coolant, inpreference water. It is, however, also possible to manufacture thethin-walled container itself out of a material, which absorbs or storescoolant.

[0018] It goes without saying, that it is also possible to cool thethin-walled container by means of a suitable coolant, e.g. by sprayingwater, air or a mixture of both media onto the thin-walled container.Also possible is the injection of water droplets or of a differentcoolant into the thin-walled container during its inflation, so that itssurface is cooled from the inside. This, for example, can be combinedwith the introduction of a liquid or gaseous component utilised for thecleaning operation.

[0019] A further preferred possibility of protecting the thin-walledcontainer consists of introducing the thin-walled container into thevessel to be cleaned inside a suitable protective device. This isimplemented, for example, by means of a protective device attached tothe cleaning device, e.g. a protective bell or funnel attached to andaround the lance. The thin-walled container can be stored in theprotective device in uninflated condition. The protective device isdesigned in such a manner, that it provides the thin-walled containerwith the possibility of a substantially free expansion as soon as it isinflated. This can e.g. be realised by an opened protective device or byone which opens by a force or by pressure, resp. An opening of theprotective device arranged on the container side, i.e. the front end ofthe lance, may be equipped with a cover. A cover of this kind inpreference is thin-walled, easy to open, resp., to release, so that itcan be separated from the protective device by an expanding thin-walledcontainer. A cover is preferably made out of materials, which arecapable of being soaked with coolant, such as, e.g., a piece of paper,jute, etc. Depending on the construction of a cover, the completeprotective device can be enclosed by it. With this, a thin-walledcontainer as well as a protective device are simultaneously protected,e.g., cooled.

[0020] In a preferred embodiment, an indirect, passive cooling system isutilised both for the thin-walled container as well as for the lance,this for the reasons already mentioned above. A passive cooling for anexplosive mixture and a lance is independent of coolants activelybrought in from the outside during the cleaning process itself, i.e.,with the lance in the introduced condition. A passive lance cooling inpreference takes place by the application of suitable materials aroundthe pipe conducting gas and/or liquid, by manufacturing the pipe or thesupply lines out of suitable materials. These, for example, areinsulating, substantially heat-resistant materials or materialarrangements and/or materials capable of absorbing coolants. Examplesfor the latter kind are absorbent materials, such as paper, cotton-woolor fabrics, which prior to being used are soaked in water or anothercoolant. For the protection against damage to a cooling layer, externalprotective layers may be affixed. In the case of absorbent paper, thiscould be a simple bandaging with fabric. It is, however, also possibleto apply a more permanent protective layer made out of, for example, ametal screen or—webbing or a second metal pipe. Materials absorbingcoolants are capable of releasing them again when required and as aresult of the evaporation cooling produced are capable of cooling thepipe or the thin-walled container. Passive cooling systems may also be,for example, dense metal webs or ceramics, which are capable ofabsorbing coolant in hollow spaces or pores. It is also conceivable toconstruct a passive cooling system out of heat absorbing materials.Materials of this kind are in a position to absorb heat and to store itinstead of conducting it onwards. Examples for this are materials, whichwithin a suitably chosen temperature range are subject to a phasechange, typically solid to liquid (so-called, phase change materials'(PCM)). A further example for an insulating lance cooling system aredouble pipes, which may be filled with insulation material.

[0021] If so required, the most diverse cooling methods and protectivedevices may also be combined, made do without or complemented.

[0022] The ignition of the explosive gas mixture, resp., liquid—/gasmixture, with or without thin-walled container or protective envelope,resp., takes place with means known from prior art. In preference thisis implemented by means of an electrically triggered spark ignition, byauxiliary flames or by a pyrotechnic ignition with the help ofcorrespondingly attached ignition means and ignition devices. The meansof ignition are preferably attached in the region of one of the ends ofthe lance, to a pipe itself or to the thin-walled container. Theactuation of the ignition device as well as the sequence of an inflow ofthe gas and/or the introduction of liquid components in preference takesplace by means of a control system.

[0023] The sequence of a blasting operation in a hot vessel in apreferred embodiment takes place as follows:

[0024] Gas-pressure vessels by means of the actuation of correspondingvalves are filled with the corresponding gases, e.g. acetylene or ethaneand oxygen and the required gas quantities and—pressures out of pressuregas cylinders.

[0025] At one end of a pipe a thin-walled container (for example, madeof plastic material, a balloon- or sack-like envelope or a bag/sack) isattached, e.g. plugged on, clamped on or glued on with adhesive tape,and/or stowed in the protective device in folded condition.

[0026] If so required, a head cooling is activated, e.g., a protectiveenvelope (insulating and/or cooling) attached, resp., soaked withcoolant and/or the cooling started together with the gas.

[0027] The lance is introduced into the vessel to be cleaned from theoutside, e.g. through an access opening, so that the end of the pipeincluding the thin-walled container is placed in front of the surface tobe cleaned.

[0028] The opening of the valves of the gas pressure vessels starts thefilling of the thin-walled container with the gas mixture.

[0029] The ignition device is actuated and an explosion triggered.

[0030] Individual steps of the sequence mentioned above of a blastcleaning process in accordance with the invention may also besupplemented and/or automated with intermediate steps. For example, thetriggering of an explosion process may be connected with safetymechanisms. These in preference start the gas supply from the pressurevessels to the thin-walled containers, or in general into the vessel tobe cleaned and interrupt this connection before the actual explosiontakes place, e.g., by means of an activation of the means of ignition.This prevents, for example, blowbacks into the supply lines anduncontrolled detonations. In addition, the cleaning process may alsoinclude a device cleaning step. This is implemented, for example, bymeans of a blowing-through with compressed air of the lance, resp., ofindividual pipes following the explosion.

[0031] In the following, embodiments of the device for the cleaningmethod for caked and slag contaminated vessels according to theinvention are explained in more detail on the basis of exemplary andschematically drawn figures.

[0032] These illustrate:

[0033]FIG. 1 a simplified depiction of an embodiment of the device inaccordance with the invention,

[0034]FIG. 2 a further embodiment of the device according to theinvention,

[0035]FIG. 3 a third embodiment of the device in accordance with theinvention.

[0036] In FIG. 1, a device 10 for carrying-out the cleaning processaccording to the invention is illustrated. The device 10 includespipe-like supply lines 1, 2 through which, in preference after theirpositioning, different gases, e.g., oxygen 3 and ethane 4, but alsoliquid fuels or oxidising agents are conducted to the proximity of thewall 5 to be cleaned. The gases 3, 4 and/or liquids in the zone of thewall contamination with dirt 6 form an explosive mixture 7. By means ofan ignition device 8, which is capable of being controlled and actuatedfrom outside the vessel or installation to be cleaned, the explosivemixture 7, for example, by the generation of an ignition spark 9 isignited. The explosion may also be triggered by an ignition devicelocated in the zone of the gas mixture 7, e.g., on the supply lines 1,2. The supply lines 1, 2 and the ignition device 8, here are designed insuch a manner, that the ignition spark 9 does not come to be situateddirectly in front of the end of a supply line 1, 2, in order to preventa blowback of the cleaning device 10, resp., a backfire into the supplylines 1,2. This can be implemented, in that the ignition spark 9 comesto be situated in the zone between the ends of supply lines 1, 2 ofdiffering lengths.

[0037] The supply lines 1, 2 and the ignition device 8 or parts of itmay also be jointly accommodated in a pipe-like envelope, e.g., in apipe. The device 10 is preferably also equipped with a cooling system.The cooling in preference takes place by means of evaporation of thecoolant, which cools the supply lines 1, 2 or the possibly presentcommon envelope. An active cooling takes place, for example, by means ofan air—and or water supply from outside in—and/or through the supplylines 1,2.

[0038] In case of a thin-walled container possibly present on the device10 for the protection of the gases against dilution, a head coolingsystem for the lance is in preference constructed as a protectiveenvelope soaked with coolant. The head cooling system may also bedesigned as a coolant supply conducted right into the container. In thismanner, the thin-walled container, resp., the gas—or gas/liquid mixturecontained in the container is cooled. The materials utilised for thesupply lines 1, 2 and/or for a common pipe in addition preferablypossess thermal insulation characteristics, in order to protect the gas3, 4 or the liquid contained in it against external thermal influencesby, e.g., flue gas.

[0039] In FIG. 2 a further exemplary device for the implementation ofthe cleaning process in accordance with the invention is illustrated. Acoolable, resp., insulated lance 20, comprising an envelope 21 and aninner pipe 22, at one of its ends comprises connections 23 for the gassupply. Also situated in the zone of this end of the lance 20 is asuitable means of ignition, e.g., a spark plug 19, with which anexplosive gas mixture is capable of being ignited, in preferenceelectrically. The envelope 21 protects the lance 20 and the gas or gasmixture present inside it against being heated up. In preference itcomprises absorbent material, e.g. paper, and in addition it may beequipped with a protective layer surrounding the absorbent material,e.g., an absorbent fabric or a heat-reflecting foil-like envelope inpreference equipped with openings. A possible protective layer, notillustrated in more detail here, substantially serves to prevent or toreduce the peeling-off, resp., damaging of the material of the envelope21 serving as an absorbent or storage device for the coolant by externalmechanical influences. A protective layer may also be equipped withadditional absorbent or insulating characteristics.

[0040] Attached to the other end of the lance 20 there is a thin-walledcontainer 25, here already inflated, and a protective bell 27. Thethin-walled container 25 is attached to the inner pipe 22 in such amanner, that it is inflated by the gas or gas mixture flowing throughthe inner pipe. The thin-walled container comprises a substantiallygas-tight plastic envelope 25 a, e.g., a plastic sack made out ofpolyethylene and a protective envelope 25 b surrounding the plasticenvelope 25 a. The protective envelope 25 b in preference is an envelopemade out of absorbent paper, which is connected with the plasticenvelope 25 a, in preference glued to it. Prior to the utilisation ofthe lance 20, i.e. prior to the introduction of the lance 20 into aninstallation to be cleaned, the paper envelope and the sheathing 21 ofthe lance 20 are covered with coolant, e.g. soaked with water. Thethin-walled container 25 is stowed in the protective bell 27 in foldedcondition. On top of the protective bell preferably there is anadditional cover soaked with coolant (not illustrated in detail), inorder to additionally cool the thin-walled container inside and ifnecessary to protect it from mechanical influences. Following theintroduction and positioning of the lance into resp. in the vessel to becleaned, the thin-walled container 25 upon inflation leaves theprotective bell 27. In doing so, it is protected from the heat of theflue gases by the water-soaked paper envelope and the inner pipe 22 bythe sheathing 21. The protective bell 27 has a slightly conical shapeopening outwards like a beaker, in order to give the inflated envelopeor the balloon-like container sufficient space. A protective device, forexample, has the shape of a hollow cone or hollow cylinder or else of abowl. In preference it comprises an opening located on one side for thepassage of the supply line or lines and on the other side an opening fora thin-walled container. A protective device may also be constructedwith double walls, so that a possible internal space is filled, resp. isable to be filled with insulating material or coolant. The protectivebell 27, the sheathing 21 or another protective device are permanentlyattached to the lance. They may, however, also be constructed in such amanner, that they are able to be slid over the lance or laid around itand positioned in different ways. This if so required makes possible aneasy replacement of a protective device following a cleaning process.For technical and economical considerations, however, for protectivedevices if at all possible heat-resistant materials are utilised.

[0041] The connection for the gas supply 23 is affixed to the inner pipe22 and connects two gas supply lines 29, 30 with the lance 20. One ofthe gas supply lines 30 is connected with a first pressure vessel 34through a solenoid valve 32, wherein this vessel itself is connectedwith a commercially available first gas cylinder 36 through a fourthvalve 38, e.g., an oxygen cylinder. The second gas supply line 29 inessence is constructed in the same manner, i.e. it is connected with asecond pressure vessel 33 through a second solenoid valve 33. Thisvessel in turn is connected with a second commercially available gascylinder 35 through a third valve 37. The second gas cylinder 35correspondingly contains a combustible gas, such as, for example,acetylene, ethylene or ethane.

[0042] After opening the third and fourth valves 37, 38, the pressurevessels 33, 34 are filled with the corresponding gases. A fill pressurealready proved by trials lies at max. 15 bar, wherein the pressurevessel volumes, for example, have values of 1.5 l for ethane and 5 l foroxygen and typically an overall gas volume of 100 l-200 l is utilisedfor the cleaning of customary vessels. The ratio of the volumes of boththe pressure vessels in preference corresponds to the stoichiometricratio of the two gases for a complete combustion. The pressures of thegases in the pressure vessels determine the power of the explosion andare able to be adjusted through reducing valves on the gas cylinders 35,36. These pressures are preferably the same.

[0043] By means of an external pressure switch 39 connected with thespark plug 19 on the lance 20, the detonation process is started. Thesequence in preference is controlled with a control system 40, e.g. arelay control system. The control paths are indicated in the Figure asdashed lines, wherein the signal direction is indicated with arrows.First of all the solenoid valves are briefly opened, e.g. for a fewseconds. During this time period the gas content of the pressure vessels33, 34 flows into the lance 20 through separate gas supply lines 29, 30.There the components are mixed and conducted into the thin-walledcontainer 25 through the inner pipe 22, wherein they inflate it. In apreferred embodiment of the cleaning device, the gas supply lines 29, 30are maintained separate in the inner pipe 22 of the lance, so that thegases are only mixed inside the thin-walled container 25 and there forman explosive gas mixture.

[0044] After the closing of the solenoid valves 31, 32, in preferenceafter a selected time delay of, e.g. 0.5 sec, the ignition device isactuated and the explosion is triggered. Depending on the selectedconstruction of the gas supply, the spark plug 19 or the ignition deviceis correspondingly positioned on the lance. The inflation process of thethin-walled container 25 amounts to a few seconds, typically 1-3 sec,e.g., 2 sec.

[0045] Following the ignition of the gas mixture, the inner pipe ispreferably cleaned of the residues of the explosion, e.g. slag. Thistakes place, for example, by means of compressed air, which is sentthrough the inner pipe 22. For this purpose, one of the gas supply lines30 is equipped with an additional valve 41, which is connected with acompressed air reservoir 42, e.g. a compressed air compressor or acompressed air cylinder. This additional valve 41, here depicted as asolenoid valve, preferably is also capable of being driven and actuatedautomatically.

[0046] If for the cleaning not only gaseous, but also, resp. exclusivelyliquid materials are utilised, then the volume of the thin-walledcontainer 25 may be kept correspondingly small. It is then made out of acorrespondingly suitable material, e.g. out of substantiallyliquid-tight plastic envelopes.

[0047]FIG. 3 illustrates a third embodiment of the device in accordancewith the invention. It comprises an exemplary construction of a coolablelance 50. A majority of the reference marks are the same as in FIG. 2.These correspondingly refer to the same exemplary characteristics andelements and not all of them are mentioned anymore at this point. Thecoolable lance 50 comprising an outer pipe 51 and an inner pipe 52, atits end is equipped with connections 23, 24 for the gas supply, as wellas for the cooling. A coolant, e.g. an air-water mixture, is conductedbetween the outer 51—and inner pipe 52. It exits at the end of the lance50, which is indicated by arrows. At this second end of the lance 50,once again a protective bell 27 for the thin-walled container 25 isattached. Depending on the flow speed or the distance of the coolantoutlet opening of the lance 50 from the protective bell 27, resp., thecoolant conducted through the lance 50 is also able to cool theprotective bell 27.

[0048] The connection 24 of the cooling system is equipped with acooling connection valve 28, e.g. a manually operated valve. Actuatingit enables switching on and—off the cooling system as required. Inpreference also the production of a certain mixing ratio of differingcoolants is made possible, here represented by two connection linesor—hoses 24 a, b, respectively.

[0049] A lance cooling system designed in this manner is in preferenceactivated prior to the introduction of the lance 50 into a hot vessel.Typically it remains switched on for the whole time period, during whichthe lance is subjected to the heat. An active lance cooling system ofthis kind is also capable of being included in a control system 40.Naturally it is also possible to introduce a coolant through a coolantconnection at one end of the lance 50 and to have it flow back again tothe same end. This would be possible, e.g. in the case of an outer pipe51 closed at one end with a substantially U-shaped or concentric coolantsupply system.

[0050] The cleaning method according to the invention with the devicedescribed in FIG. 3 proceeds in a similar manner as that of FIG. 2:Soaking of a thin-walled container 25 with coolant, activation of thelance cooling system, introduction and positioning of the lance, fillingof the pressure vessels 33, 34 with the required gas quantities,triggering of the ignition process by means of actuating a pressureswitch 39. The gas, resp. the gases flow through the lance 50 andinflate the thin-walled container 25. This container is initiallyprotected against heating up by the protective bell 27, thereuponsubstantially by the soaked protective envelope 25 b. When the requiredgas volume has reached the thin-walled container 25, the explosive gasmixture is ignited by means of suitable means of ignition 19. Inpreference, following the carrying out of the cleaning process, theinner pipe 52 and possibly also the outer pipe 51 is cleaned in acleaning step, e.g. by means of compressed air it is freed of slag andwater.

[0051] The utilisation of a thin-walled container in accordance with theinvention presented here provides the advantage, that it is exceedinglycheap to manufacture. An additional advantage of a thin-walled containermade of a plastic sack enveloped with paper is the fact, that while anypossible sparking can perforate the plastic sack, the envelope, however,continues to protect the explosive gas or—gas mixture. A protectiveenvelope made of absorbent material may be constructed with severallayers. By means of the, for example, provision of several single-layerprotective envelopes, the container therefore is capable of beingadapted to temperatures in differently hot vessels. By exploiting theevaporation cooling of suitable coolants, no supply of coolant into orthrough the lance, resp., is necessary during the actual cleaningprocess.

1. Method for the cleaning of contamination with dirt, resp. caking orslag deposist (6) in vessels and installations by means of blastingtechnology, wherein an explosive mixture (7), which in part is gaseous,is brought into the proximity of the dirt contamination, resp. caking orslag deposits (6) and the explosive mixture (7) thereupon is made todetonate.
 2. Method for the cleaning of contamination with dirt, resp.caking or slag deposits in vessels and installations by means ofblasting technology during the operation of the installation, resp. whenthe vessel is hot, characterised in that a thin-walled container (25) bymeans of a pipe-like device, resp. lance (20) is brought into theproximity of the contamination with dirt, resp. caking or slag deposits(6), that a partially gaseous, explosive mixture (7), resp. liquid orgaseous components forming an explosive mixture are introduced into thethin-walled container (25), and that the explosive, partially gaseousmixture (7) is made to detonate.
 3. Method for the cleaning ofcontamination with dirt, resp. caking according to one of the precedingclaims, characterised in that a thin-walled container (25) is inflatedby gases (3, 4) or by the explosive mixture (7).
 4. Method for thecleaning of contamination with dirt, resp. caking according to one ofthe preceding claims, characterised in that the explosive, partiallygaseous mixture (7) is mixed in the proximity of a surface to be cleaned(5), resp. in a thin-walled container (25).
 5. Method for the cleaningof contamination with dirt, resp. caking according to one of thepreceding claims, characterised in that gases (3, 4) or the explosivemixture (7) flow out of at least one pressure vessel (33, 34) into apipe-like device, resp. a lance (20).
 6. Method for the cleaning ofcontamination with dirt, resp. caking according to one of the claims1-5, characterised in that the explosive mixture (7) is produced by themixing of a gaseous fuel (4) and a gaseous oxidising agent (3). 7.Method for the cleaning of contamination with dirt, resp. cakingaccording to one of the claims 2-6, characterised in that as thin-walledcontainer (25) an inflatable envelope, such as, for example, a flexibleplastic envelope (25 a) or an elastic, balloon-like container isutilised.
 8. Method for the cleaning of contamination with dirt, resp.caking according to one of the claims 2-7, characterised in that thethin-walled containers (25) and/or the pipe-like device, resp. the lance(20) is cooled.
 9. Method for the cleaning of contamination with dirt,resp. caking according to claim 8, characterised in that the thin-walledcontainer (25) is cooled by a protective envelope (25 b) soaked withcoolant.
 10. Method for the cleaning of contamination with dirt, resp.caking according to one of the claims 2, 5 to 9, characterised in thatduring the introduction of and in the positioned condition of thepipe-like device, resp. lance (20), no coolant flow into the pipe-likedevice, resp. the lance (20) or into the thin-walled container (25)takes place.
 11. Device for the cleaning of contamination with dirt,resp. caking in vessels and installations for utilisation of the methodaccording to claim 1, characterised in that it is a lance designed inthe manner of a pipe and comprises means of supply (1,2) for conductingliquid or gaseous components, or an explosive, partially explosivemixture (7) into the region of a wall zone (5) of the vessel that iscontaminated with dirt, resp. with caking (6).
 12. Device for thecleaning of contamination with dirt, resp. caking in vessels andinstallations for the utilisation of the method according to one of theclaims 2-10, characterised in that it is a lance designed in the mannerof a pipe and comprises means of supply, in order to conduct anexplosive, partially gaseous mixture (7) or liquid or gaseous componentsforming an explosive mixture into the region of the wall zone of thevessel that is contaminated with dirt, resp. with caking, and that itcomprises means (25) for the prevention of the dilution of the at leastpartially gaseous components and/or of the explosive mixture (7), saidmeans (25) for the prevention of dilution are located at the end of thelance designed in the manner of a pipe that is leading into the vessel.13. Device according to one of the claims 11 or 12, characterised inthat it comprises means of ignition (8) for the ignition of theexplosive mixture or for the components forming an explosive mixture(7).
 14. Device according to claim 12 or 13, characterised in that themeans for the prevention of the dilution of the at least partiallygaseous components and/or of the explosive mixture (7) is a thin-walledcontainer (25).
 15. Device according to one of the claims 12 to 14,characterised in that it comprises means for cooling the shaft of thelance and/or a head cooling system.